Heat pad switch



Nov. 16, 1954 H. LAYLON 2,694,760

HEAT PAD SWITCH Filed June 20, 1950 INVENTOR.

HARRY L. LAYLON BY 3 mm if Emmi/ 1% {74mm ATTORNEYS United States Patent f HEAT PAD SWITCH Harry L. Laylon, Rochester, N. Y., assignor to Bickford gros. Co., Rochester, N. Y., a corporation of New ork Application June 20, 1950, Serial No. 169,124

1 Claim. (Cl. 200-167) This invention relates to improvements in electric switches primarily intended for heating pads, but useful wherever a switch is required in a flexible electric cable.

One object of the invention is to provide a switch of the character described which can be readily operated with one hand and wherein the desired adjustment of the switch can be determined by the thumb of the user as he turns the switch.

A further object of the invention is to provide a switch of the class described having an illuminated indicator showing all settings of the switch without requiring separate contacts for the lamp.

A further object of the invention is to provide a switch of the character described which is formed entirely of molded plastic parts except for the metal contacts and screws, and which can be easily and rapidly assembled with unskilled labor.

A further object of the invention is to provide a rugged switch of attractive appearance at a low manufacturing cost.

In the accompanying drawings there is illustrated a preferred form of the improved switch, and in the said drawings:

Figure 1 is a plan view of one-half of the open switch, showing the various fixed contacts;

Fig. 2 is a section on line 22 of Fig. 1;

Fig. 3 is a plan view of the switch showing the rotatable dial for making the various contacts;

Fig. 4 is a transverse section on line 4--4 of Fig. 2; and

Fig. 5 is a wiring diagram showing the several circuits which are selectively closed when the switch is used in a heating pad.

Referring to the drawings, particularly to Fig. 1, 1 indicates one-half of the molded plastic casing forming the body of the switch. As shown, the casing is of a flattened pear-shaped contour with the two wire cables for connection to the power line entering the broader end of the casing through a groove 2 coincident with the longitudinal axis of the casing. One wire 3 of the two-wire cable is attached to a screw 4 which is set in a tapped hole in a rib 5 molded in the inner face of the part 1. A small wire 6 leads from the screw 4 through a resistance 7 to one binding post of a lamp socket 8 which is fixed to the part 1 in position to support a signal lamp 9 provided to illu minate the translucent marking on the dial of the switch as will be later described. The other wire 10 of the power cable is connected to a binding post and contact 11 on the face of a fiber or plastic disk 12 which is attached to part 1 of the casing by screws seated on tapped holes in the rib 13 molded on the part 1. The binding post 11 is also connected by a wire 14 to the other terminal of the lamp 9 so that the lamp 9 will be energized whenever the wires 4 and 10 are connected to the power line, regardless of the position of the switch.

In Fig. 5 a typical heat pad circuit is shown as controlled by the improved switch. As here shown, the circuit comprises two heating elements 15 and 16 of different capacities which separately constitute the low and medium heating units of the pad. The high heating effect is accomplished by connecting both circuits in parallel to the source of power. To that end the heating element 15 is connected to a binding post and contact 17 on the disk 12 and the heating element 16 is connected to a binding post and contact 18 on the disk 12 and a switch member 19 is provided, which in three of its four positions of adjustment connects either or both contacts 17 and 18 to the contact 11, and in its fourth or ott posi- 2,694,760 Patented Nov. 16, 1954 tion disconnects both contacts 17 and 18 from the contact 11. The switch member 19 consists of two segmentshaped parts connected by a cross member which is attached at its center to a pin 20 mounted for rotation inthe disk 12. The pin 20 projects axially from the inner face of the rotatable dial 21 which is manipulated by the user of the pad to adjust the switch to its different positions. The dial 21 consists of a molded plastic disk hav-- ing a central hub portion 22 which rotates in a hole inthe wall of part 1 of the casing, the pin 20 being set inthe plastic at the center of rotation of the hub 22, whenthe dial 21 is molded. The dial 21 is circular and of the same diameter as the upper semi-circular portion of the casing. The casing is reduced in thickness throughout a circular area corresponding with the dial 21 to an extent equal to the thickness of the dial so that the outer face of the dial forms a continuation of the surface of the casing.

The dial 21 is formed with eight concentric holes 23 underlying which is a ring 24 of transparent plastic having legends as shown in Fig. 3, indicating the different positions of dial adjustment. The lamp 9 is supported beneath the path of movement of the holes 23 so as to illuminate the legend at one of the holes at each position of adjustment, the illuminated legend indicating the circuit which is closed at that position of the switch.

The contacts 11, 17 and 18 project through the disk 12 and are formed with spring extensions which press against the face of the segments of the contact 19. The ends of the spring extensions of the contacts 11, 17 and 18 are bent slightly outward as indicated in Figs. 2 and 4 and the segments of the contact 19 have radial grooves 26 one of which in each of the operating positions of the switch registers with the ends of one of the spring extensions and serves to check the movement of the dial in such position. A similar locking member 27 is attached to the disk 12 in position to hold the dial 21 in its off position.

The operation of the switch will be apparent from the foregoing description. The lamp 9 will be energized whenever the heating pad is plugged into the circuit, thereby illuminating whichever portion of the transparent disk overlies the lamp 9. The contact members 11, 17, 18 and 27 are all so shaped as to lightly hold the rotating contact in one of the eight positions corresponding with the eight holes in the dial of the rotating switch member but at the same time to permit the switch member to be turned readily in either direction. The dial of the switch member is of the full diameter of the casing and consequently may be readily turned by the thumb engaging any portion of the edge of the switch member which is indented, as shown, to provide ribs or teeth in varying number to indicate the particular circuit which is closed. It will be noted that the three different circuit arrange ments and the off position of the switch are each obtained on two different positions of the rotating switch member, the two positions being diametrically opposite to each other so that the rotating switch never has to be turned more than two spaces to get any desired change of setting.

In the preferred arrangement the high position lies between low and medium so that to operate high from either direction an intermediate contact will be made with either low or medium. By the arrangement shown the teeth adjacent the cable at the top of the switch indicate the particular circuit that is closed. Hence in manipulating the switch when it is in position not to be seen the user can readily determine by pressing his thumb against the edge of the rotating switch member at the position adjacent the cables which particular circuit is closed and shift the contacts to the desired circuit by turning the switch member in either direction.

My improved switch is particularly designed for easy assembly. All parts of the switch are carried by part 1 of the two-part housing so that by loosening the two screws which hold the two parts of the housing together all the working parts of the switch may be inspected without disturbing any of the connections. If necessary to examine the contacting faces the two screws which hold the disk 12 in place and the lock washer at the end of the spindle of the rotating contact member can be removed and the disk 12 removed from the spindle without interfering with the circuit-connections- In assembling the switch the lamp-supporting member 8 is fastened in posi tion and its resistance 7 and conductor 6 attached to the binding screw 4. The disk 12 is then attached to the housing part 1 and the rotatable switch member carrying the contact segment is inserted through the opening in the face of the housing member 1 with its spindle projecting through the hole in the disk 12. The lock Washer is then forced over the end of the spindle to hold the contact members in proper relative position. The ends of the various conductors are then attached to their respective binding posts which are on the exposed face of the disk or an exposed portion of the housing 1. The cover part of the housing 1 is then fastened in place and the assembly is completed.

In the accompanying drawings and foreging specification I have described in detail a preferred embodiment of my invention in the form. adapted for manufacture, but it will be obvious that the structural details of the same may be variously modified without departing from the spirit of the invention or the scope of the appended claim.

I claim:

In a switch of the class described, the combination of two members having portions of their perimeter of semicircular contour and adapted to be fastened together to form a housing, said housing having openings for the passage of electrical conductors to the interior of said housing, a rotatable switch member carried by one housing member and having a rotatable contact within said housing, fixed contacts supported in said housing adjacent said rotatable contact, said rotatable switch member comprising a disk whose edge is co-extensive with said semicircular portion of said housing, said contacts being arranged to establish the same circuit atdiametrically opposite positions of said rotary member, the edge of said disk being exposed at one such position and a light for illuminating the portion of the disk at the diametrically oppo-- site position.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 19,200 Meuer June 5, 1934 2,415,858 Youhouse Feb. 18,. 1947 2,505,938 Biermann et al May 2, 1950 2,522,423 Youhouse Sept. 12, 1950 FOREIGN PATENTS Number Country Date 671,668 Germany Feb. 11, 1939 

